Such an adjusting device comprises at least a fixed lower rail (hereinafter guide rail) and an upper rail (hereinafter sliding rail) that is adjustable and guided in the longitudinal direction along the guide rail. In such a longitudinal adjustment device two guide rails are disposed in parallel with each other in the longitudinal direction of the motor vehicle, while the motor vehicle seat is mounted to the corresponding sliding rails. The sliding rails are adjustable and guided in the longitudinal direction along the lower rails and can be secured in their positions with respect to the lower rails by means of a locking device.
FIG. 1a shows a first example of such a conventional adjusting device 100 comprising a guide rail 102, a plurality of through holes 106 being formed in a bottom thereof, and a sliding rail 101 having a plurality of through-holes 105. Guide rail 102 and sliding rail 101 are assembled together to form a rectangular hollow inner space 103. A locking device 110 having a plurality of spring-biased locking pins 111 is fixed to an upper side of the sliding rail 101 and is used for locking the position of the sliding rail 101 relative to the guide rail 102 at selectable positions by engagement of the locking pins 111 with a plurality of openings 106 formed in a bottom of the guide rail 102. The locking pins 111 are guided in bores formed in a guiding web 117 fixed at a side-wall of the guide rail 102.
FIGS. 2a and 2b show further details of a conventional locking device 110 as disclosed e.g. in German Utility Model DE 20313951 U1 of the Applicant. The locking device 110 comprises a lifting lever 119 with slots 120 for engagement with the radial protrusions 115 formed at the upper ends 114 of the locking pins 111. For releasing the locking pins 111 from the holes 106 in the bottom of guide rail 2 (cf. FIG. 1a) by lifting the locking pins 111, the lifting lever 119 is lifted by pushing handling lever 121
Conventionally, positioning pins are used for positioning the guide rail 102 relative to a vehicle floor (not shown), particularly when mounting the adjusting device 100 in a vehicle. FIG. 1b shows in a magnified view an example of such a positioning pin 135, which is fixed to the bottom of the guide rail 102 by riveting so that an expanded riveted head 136 is formed at an upper end of the positioning pin 135. Usually, this positioning pin 135 (also known as locator pin) is attached to a riser 137 via a staking process, and the riser 137 is fixed to the guide rail 102.
Considering that the adjusting device 100 shown in FIG. 1a is manually actuated for adjusting the longitudinal position of the vehicle seat, a stop feature needs to be provided as indicated by the arrow in FIG. 1a, for limiting the travel stroke of the sliding rail 101 relative to the guide rail 102. More specifically, according to FIG. 1a the stop feature is implemented by the interaction of an end stop pin 130 and the opposite end of the guiding web 117 of the locking device 110. Conventionally, such stop pins 130 need to be installed after the sliding rail 101 and the guide rail 102 are married together to form the profile of the adjusting device 100, and for this purpose the stop pins 130 are usually fixed to the guide rail 102 via a staking process, as shown in FIG. 1a. 
Installing a positioning pin and a stop feature of the afore-mentioned type during assembly of the adjusting device is often difficult, given rail lengths, customer-specific floor mounting and travel requirements. Installing conventionally also requires two separate staking processes during assembly, which increases time and costs for assembly and may cause a risk of mechanical damages to the rails that might also impair the appearance of the adjusting device. Accordingly, there exists further need for improvements.
Further examples of conventional adjusting devices for longitudinal adjustment of a vehicle seat are disclosed in US 2011/0233367 A1, US 2010/0207419 A1, U.S. Pat. No. 5,209,447, U.S. Pat. No. 6,346,272 B1 and US 2005/0224680 A1.
Conventional adjusting devices of the afore-mentioned type need to be optionally configured for manual operation or automatic operation by means of an electric motor. Accordingly, there is a need to implement a stop feature as outlined above and a positioning pin in a simple and cost-effective manner.
Furthermore, there is a need for providing an enhanced method for assembly of such adjusting devices in a simple and cost-effective manner.